Device for cutting sheet material

ABSTRACT

A device for cutting sheet material, such as a layup of fabric sheets spread on a cutting table, includes a cutter head movable over the table and having a vertically reciprocating knife or other similar cutting tool. The cutter head is moved by numeric control relative to the table to cause its tool to follow a desired line of cut, and associated therewith is a bottom plate which moves longitudinally of the table in unison therewith between the supporting surface of the table and the bottom layer of the material to receive the lower or distal end of the cutting tool.

tilted States Patent [191 Pearl May 29, 1973 DEVICE FOR CUTTING SHEET[73] Assignee: Gerber Garment Technology, East Hartford, Conn.

[22] Filed: July 31, 1970 [21] Appl. No.: 59,899

3,495,492 2/1970 Gerber et a1. ..83/374 3,589,222 6/1971 Sederberg..83/925 CC 3,548,502 12/1970 Baldwin ..83/925 CC 3,511,124 5/1970 Bruns.83/925 CC 3,548,699 12/1970 Gerber.... 83/925 CC 1,172,058 2/1916Scheyer... 83/925 CC 3,465,630 9/ l 969 Bruns ..83/424 PrimaryExaminer-J. M. Meister Attorney-McCormick, Paulding and Huber [57]ABSTRACT A device for cutting sheet material, such as a layup of fabricsheets spread on a cutting table, includes a cutter head movable overthe table and having a vertically reciprocating knife or other similarcutting tool. The cutter head is moved by numeric control relative tothe table to cause its too] to follow a desired line of cut, andassociated therewith is a bottom plate which moves longitudinally of thetable in unison therewith between the supporting surface of the tableand the bottom layer of the material to receive the lower or distal endof the cutting tool.

13 Claims, 17 Drawing Figures PATENIE #112 91973 sum 1 [1F 7 INVENTORDAV/D RPEARL Affornevq PATENTH; HXY 2 91973 SHEET 2 OF 7 PATENTEL HKY 291375 SHEET 6 [IF 7 PAIENI M29 1975 3, 7 5 5 O SHEET 7 OF 7 BACKGROUNDOF THE INVENTION This invention relates to devices for cutting sheetmaterial, particularly material which is by itself relatively thick orwhich is comprised of a large number of individually thin layers laid upon top of one another to form a relatively thick layup.

The cutting device of this invention has particular utility in thecutting of layups of fabric such as are used when making clothing,upholstery or the like, but may also be used for the cutting of variousother different sheet materials. In the cutting of fabric layups it iscustomary to spread the fabric onto a cutting table and to then cut itby means of a hand-guided cutter including and electrically poweredvertically reciprocating cutting blade. When material is cut by such areciprocating blade, it is necessary that the blade in the lowermostextent of its stroke extend at least a small distance beyond the lowerlayer or surface of the material in order that the full thickness of thelayup be cut. In the handguided cutting tool, the projection of theblade below the lower surface of the layup is accommodated by a base onthe cutter which moves between the supporting surface of the table andthe lower surface of the mate rial. The base is connected to the mainportion of the cutting tool, which includes the motor and other partsand which is located above the layup, by a relatively sturdy sheathwhich partially surrounds the blade and which extends through the slitin the fabric made by the blade.

The present invention relates to a cutting device which also uses avertically reciprocating blade and a bottom member movable under thelayup for receiving the projecting lower end of the blade but which isparticularly adapted for use with a numerical controller for dictatingits movement and which is not dependent on the use of a relativelysturdy sheath for moving the base in unison with the blade and theremainder of the cutter. Therefore, in the device of this invention, theblade sheath may be made of a relatively small size to make the bladecapable of cutting sharp corners and of otherwise being easilymaneuvered through the fabric. Alternatively, the sheath may beeliminated entirely, or at least made unconnected with the bottom memberso as to be vertically movable with the blade, making it possible toexecute plunging cuts with the blade to start a cut from any point inthe layup rather than requiring a cut to be always started from the edgeof the layup as is the case when the base or bottom member is connectedto the upper portion of the cutter bya sheath fixedly connected to bothsuch parts.

In the cutting of some materials a reciprocating blade which is merelycantilevered from the cutter head without being restrained at its bottomend may tend to deflect away from its desired cutting axis as it ismoved through the layup and, therefore, may not provide a straight outthrough the entire thickness of the layup causing a piece cut from anupper layer of the layup to differ in shape and size from a piece cutfrom a bottom layer of the layup. In accordance with one embodiment ofthis invention, therefore, the bottom member includes a guide which isengageable with the lower or bottom end of the blade and which guide ismoved in unison with the movement of the upper portion of the cutter sothat the blade is therefore supported and moved at both of its ends toprevent deflection of its lower end.

SUMMARY OF THE INVENTION sheet material spread thereon. The cutter headis supported for movement both longitudinally and transversely of thesupporting surface to enable the cutting tool thereof to follow anydesired line of cut on the layup. Associated with the cutter head is abottom -member which moves over the supporting surface be tween it andthe lower layer of the material to be cut. This bottom member isconnected with the cutter head for movement longitudinally of thesupporting surface in unison therewith and includes a slot extendingtransversely of the cutting table for accommodating the lower end of thetool. In accordance with various specific aspects of the invention thisslot may include a transversely moving guide for engaging the lower endof the tool and driven transversely in unison with the transversemovement of the cutter head, may include a penetrable filling materialsuch as a strip of bristles, a strip of foam plastic, or a strip ofself-healing material, or may merely be an empty slot with the lowerlayer of the fabric layup being spread on top of a layer of heavy paperor cardboard or other relatively stiff expendable sheet material whichsupports the layup as it passes over the slot and provides an anvilsurface for reacting the downwardly directed forces of the reciprocatingtool.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing acutting device embodying this invention.

FIG. 2 is an enlarged plan view showing a portion of the cutting deviceof FIG. 1.

FIG. 3 is a still further enlarged vertical sectional view taken on theline 33 of FIG. 2.

FIG. 4 is a plan view taken on the line 4-4 of FIG. 3.

FIG. 5 is a view, somewhat similar to FIG. 2, but with various partsbeing broken away and with others being omitted to show various detailsof the cable drive system between the cutter head and the guide for thedistal end of the cutter tool.

FIG. 6 is an enlarged vertical sectional view taken on the line 6-6 ofFIG. 5.

FIG. 7 is a view similar to FIG. 3 but shows another embodiment of thecutting device of this invention including a vacuum means for holdingthe material to be cut tightly in place on the supporting surface.

FIG. 8 is a view similar to FIG. 3 but shows a cutting device comprisingstill another embodiment of this invention.

FIG. 9 is a view similar to FIG. 8 but shows the cutting tool and sheathmoved to a raised position above the top surface of the material to becut.

FIG. 10 is an enlarged perspective view of the tool guide used in thedevice of FIG. 8.

FIG. 1 l is a somewhat schematic view illustrating the cable mechanismutilized for moving the guide transversely and rotationally in unisonwith the transverse and rotational movement of the blade.

FIG. 12 is a fragmentary perspective view ofa cutting device comprisinganother embodiment of this invention.

FIG. 13 is a sectional view taken generally on the line 13-13 of FIG.12.

FIG. 14 is a sectional view generally similar to FIG. 13 but showing acutting device comprising another embodiment of this invention.

FIG. 15 is a fragmentary perspective view showing a portion of thebristle element used in the device of FIG. 14.

FIG. 16 is a fragmentary perspective view generally similar to FIG. 12but showing a device comprising another embodiment of this invention.

FIG. 17 is a sectional view taken generally on the line 17l7 of FIG. 16.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A cutting device embodying thisinvention and particularly adapted to the cutting of layups of fabricsuch as used for making clothing or upholstery is shown at 10 in FIG. 1.Considering FIG. 1 in more detail, the device 10 includes a table 12having an upwardly facing flat supporting surface 14 for supporting thesheet material to be cut. In FIG. 1 such material is shown to consist ofa layup 16 of a large number of individual layers of fabric spread overthe supporting surface 14. The table 12 may be of a relatively longlength and may be generally similar to the spreading and cutting tablespresently often used in large scale cloth cutting operations. During thecutting operation, the layup 16 remains stationary on the supportingsurface 14.

For performing the actual cutting of the layup 16 the device 10 of FIG.1 includes a cutter head 18 which is supported above the surface 14 andincludes a cutting tool in the form of a reciprocating blade 20 whichextends downwardly from the cutter head toward the surface 14 so as tobe cuttingly engageable with the layup 16. The cutter head 18 is mountedfor movement transversely of the table 12 by being fixed to asub-carriage 22 which in turn is supported for transverse movementrelative to the table by suitable guide means such as a guide tube 24and a lead screw 26. The guide tube 24 and lead screw 26 are supportedand carried by a main carriage 28 which straddles the table 12 and issupported for movement longitudinally thereof by two racks 30, 30 onopposite sides of the table and toothed wheels or pinions 32, 32 carriedby the carriage 28 and meshing with the racks. As shown best in FIG. 2,two of the pinions 32, 32, which are located on opposite sides of thecarriage 28, are connected with one another by a transversely extendingaxle 34 to which both such pinions are fixed so as to be constrained torotate in unison thereby maintaining the carriage 28 in true alignmentwith the longitudinal axis of the table 12 and preventing it fromskewing.

Transverse movement of the cutter head 18 relative to the supportingsurface 14 is obtained by rotating the lead screw 26 which is driven byan associated motor 36, and longitudinal movement of the cutter headrelaunderstood that by combined operation of the motors 36 and 38, thecutter head 18 may be caused to move along any desired line of cut inthe plane of the supporting surface 14, one such line of out beingindicated at 40. Operation of the motors 36 and 38 is controlled by anassociated automatic controller indicated at 42. The controller 42, may,for example, be a numerical controller operating in response to inputinformation supplied by a magnetic tape reader, punched tape reader orother input device to drive the cutter head 18 along a desired line.

Of course, it should be understood that the illustrated means for movingthe carriage 28 longitudinally of the table and the sub-carriage 22transversely of the table are intended to be exemplary only and manyother suitable and different constructions of such means may be employedwithout departing from the invention. For example, the drive for movingthe carriage 28 longitudinally may, if desired, consist of only one rackand one pinion used in association with other means for guiding thecarriage along a straight lontidudinal path without skewing.

Depending on various factors, such as the size, shape and material ofthe blade, the feed rate and the nature of the material being cut, thecutting blade 20 of FIG. 1 if unrestrained at its lower or distal endmay, to an undesirable degree, tend to deflect away from its nominalcutting axis as a result of pressures applied thereto by the layup l6and arising from movement of the cutter head relative to the layup. Forexample, from FIG. 1, it will be understood that if the lower end of theblade 20 is unrestrained and the cutter head is moved either to the leftor right of the position shown, the blade as a result of its engagementwith the layup will tend to deflect to the right or left by bending awayfrom its nominal cutting axis. In FIG. 1, the nominal cutting axis isindicated generally at 44 and is the longitudinal axis of the blade whenthe blade is in its normal undeformed state. It will also be understoodthat the cutter head 18 includes a mechanism for both reciprocating theblade 20 and for rotating it about the nominal cutting axis 44 in orderto maintain the blade generally tangent to the line of cut. It will alsobe appreciated that in order to cut through the full thickness of thelayup it is necessary for the blade 20 in the lowermost extent of itsstroke to extend at least slightly beyond the lower layer of the layup,and also at the cutting zone it is necessary for the bottom layer of thelayup to be adequately vertically supported so that the blade whenmoving downwardly will move past and cut such layer rather than merelydisplace it downwardly.

In order to prevent deflection of the lower end of the blade while alsosupporting the material to be cut at the cutting zone and allowing theblade to move beyond the lower surface of the material, the device 10 inaccordance with this invention includes a guide which is engageable withthe lower end portion of the blade and which restrains such lower endportion to the position of the guide, the guide in turn being moved inunison with the movement of the cutter head 18 so that the lower end ofthe blade is supported by the guide and forced by the guide intoalignment with the nominal cutting axis. Referring to FIGS. 2, 3 and 4,the guide in the illustrated case comprises a sheath 46 which not onlyengages the lower end portion of the blade but which may and preferablydoes, as shown, extend along the full length of the blade and isattached at its upper end to the cutter head 18. The sheath 46 includesa longitudinally extending slot which receives the major portion of theblade leaving the sharp edge 29 of the blade exposed. That is, thesheath engages both the rear edge and both lateral faces of the bladeand prevents it from deflecting relative to the sheath both laterallyand rearwardly.

At its lower end, the sheath 46 is fixed to a generally cylindrical head48 which is received in a conforming circular recess in a guide block50, the sheath 46 and head 48 therefore being free to rotate relative tothe block 50 to permit rotation of the blade about the nominal cuttingaxis 44. The guide block 50 is received in a slot 52 in a bottom member54, both of which extend transversely of the table, so that as the guideblock 50 is moved along the length of the slot 52, the head 48, thesheath 46 and the lower end of the blade 20 are likewise movedtransversely of the bottom member 54.

As shown in FIG. 1 the bottom member 54 is adapted to pass between thesupporting surface 14 and the bottom surface of the layup 16. Ifdesired, and as shown in FIGS. 3 and 4, means may be provided forejecting air from the top surface of the bottom member to reduce thefriction between the bottom member and the layup by creating an aircushion therebetween. Such means include a plurality of small orifices72, 72 in the bottom member communicating with its top surface 73 andwith air distributor channels 74, 74 passing transversely through thebottom member and connected to a suitable source of air under pressure.

To provide support for the material being cut at the cutting zone theguide block 50 has an upper surface 75 flush with the surface 73 and thecircular head 48 likewise has an upper surface 77 flush with the surface75, as best shown in FIG. 3. Also as shown in FIG. 3, which shows theblade 20 in the lowermost extent of its stroke, the circular head 48accommodates the lower end of the blade and permits it to project beyondthe lower surface of the material being cut.

The movement of the guide block 50 is coordinated with the movement ofthe cutter head 18 by a cable drive system illustrated best in FIGS. 5and 6. Referring to these figures, a first cable 56 is connected at itsopposite ends to opposite sides of the sub-carriage 22 and by means ofpulleys 58, 58 on the main carriage 28 is trained into a loop includingone straight section 60 which passes through an opening 62 in the bottommember 54. A second cable 64 has its opposite ends fixed to the oppositesides of the guide block 50 and is trained into a loop by two pulleys66, 66 carried by the bottom member. The cable 64 therefore includes onestraight section 68 which is also located in the opening 62 togetherwith the section 60 of the cable 56. Within the opening 62 the twocables 56 and 64 are joined to one another by a connector 70. From FIGS.5 and 6, it will therefore be obvious that as the cutter head 18 ismoved to the right, the section 60 of its associated cable 56 is movedto the left and moved with the latter, through the connector 70, is thesection 68 of the cable 64. This movement of the cable 64 thereforecauses the guide block 50 to also be moved to the right in unison withthe movement of the cutter head. Similarly, the movement of the cutterhead to the left causes movement of the guide block 50 to the left tomaintain it aligned with the cutter head.

In the device of FIGS. 1 to 6, the material to be cut, as evident fromFIG. 1, is placed on the table 12 without the use of any supplementarymeans for holding it to prevent it from possibly shifting as a result offorces imposed thereon by the blade. If desired, however, the cuttingdevice of this invention may include any suitable means for providing aholddown for the material to restrain it against shifting. A preferredform of such means is shown in FIG. 7 and consists of a sheet of airimpervious material, such as a sheet of polyethylene, indicated at 80,spread over the top of the layup 16 and used in conjunction with a tableincluding means for supplying a vacuum to its supporting surface. Suchvacuum supplying means may take many different forms, and in theillustrated case the table 90 includes a top plate 92 containing a largenumber of perforations or passageways 94, 94 which provide communicationbetween the supporting surface and a vacuum chamber 96 located below theplate 92. The vacuum chamber 96 is, in turn, connected to a suitablesource of vacuum by a conduit 98. As a result of the vacuum applied tothe top or supporting surface of the plate by the apertures 94, 94,atmospheric pressure urges the air impervious overlying sheet 90downwardly toward the supporting surface and compresses the layup 16between it and the supporting surface to hold it relatively rigidly inplace. Because of the increased pressure on the bottom member 54 due tothe vacuum holddown, the bottom member, as shown in FIG. 7, preferablyincludes a number of wheels or rollers such as indicated at 100, 100 toenable it to be moved more easily relative to the table. The otherportions of the cutting device shown in FIG. 7 are or may be similar tothat shown in FIGS. 1 to 6, and in FIG. 7 those parts which are the sameas corresponding parts of the device 10 of FIGS. 1 to 6 have been giventhe same reference numerals as the parts of FIGS. 1 to 6 and need not befurther described.

In the device 10 of FIGS. 1 to 6, as well as the device illustrated inFIG. 7, it will be noted that the sheath 46 is vertically immovable andis fixed both to the cutter head 18 and the cylindrical head 48.Therefore, when initiating a cut with the device 10 it is necessary thatsuch cut always be started from an edge of the layup 16. In manyinstances, it may be desirable to be able to initiate a cut from a pointlocated at some distance from any edge of the layup, and to accomplishthis it is necessary that the blade and its sheath, if any, bevertically movable relative to the supporting table and the fabric layupso that it may be moved upwardly to withdraw it entirely from the layupand then moved downwardly to make a stabbing or plunging cut into thematerial. A cutting device so designed is shown in FIGS. 8 to 11.

Referring to FIGS. 8 to 11, the illustrated device includes a cuttingtable 12 and a cutter head 102,'the cutter head having a verticallyreciprocating blade 104 and an associated sheath 106. The table 12 isthe same as the table 12 of FIG. 1 and the cutter 102 is or may besubstantially similar to the cutter 18 of FIG. 1. The cutter head 102 isalso movable longitudinally and transversely of the table 12 and themeans for obtaining such movement are the same as those disclosed inFIG. 1, with the exception that the cutter head 102 is also supportedfor movement bodily vertically relative to the table 12 between alowered position as shown in FIG. 8 and a raised position as shown inFIG. 9. For example, the cutter head 102 as shown in FIGS. 8 and 9 ismoved vertically relative to the sub-carriage by a rack 105 fixed to thecutter head and a pinion 107 carried by the sub-carriage and driven by amotor on the sub-carriage.

The device of FIG. 8 includes a bottom member 108, generally similar tothe bottom member 54 of the device 10, having a slot 109 thereinextending transversely of the table and receiving a cylindrical guidemember 110. The slot 109 of the bottom member 108 and the guide member110 are so relatively shaped that the guide member is restrained tomovement along the length of the slot 109 while also being free torotate about a vertical axis.

As shown in FIG. 10, the guide member 1 10 includes a verticallyextending opening 112 having a shape conforming to that of the sheath106 and also providing clearance for that portion of the blade 104 whichprojects forwardly beyond the sheath. When the sheath is in its loweredposition, as shown in FIG. 8, the guide opening 112 receives the sheathand restrains its lower end to the position of the guide member. Thesheath in turn restrains the blade 104, and as shown in FIG. 8 in thelowermost extent of its stroke the blade 104 extends into the guidemember 110.

The guide member 110 is moved along the length of the bottom member 108in unison with the corresponding movement of the cutter head 102transversely of the table 12, and in addition to this movement it isalso rotated about its vertical axis to maintain its opening 112 inproper angular position relative to the angular position of the blade104 and sheath 108. That is, as the blade is rotated about a verticalaxis the guide 110 is likewise rotated about a vertical axis in the samedirection and to the same degree.

The means for moving the guide 110 to maintain it both angularly andlaterally aligned with the blade and its sheath may take many differentforms and may, for example, consist of a cable drive system generallysimilar to that shown schematically in FIG. 11. Referring to thisfigure, and also to FIGS. 8 and 9, the illustrated device includes abushing 111 which is vertically fixed to the sub-carriage 22 butrotatable about a vertical axis. The blade and sheath 106 pass through aconforming opening in the bushing 111 and because of the noncircularcross-sectional shape of the sheath and the conforming opening in thebushing the bushing is rotated in unison with the rotation of the bladeand sheath.

The bushing 111, as shown in FIG. 11, has trained about it two cables113 and 115. To better distinguish the two cables from one another inFIG. 11 the cable 113 is shown in broken line and the cable 115 is shownin solid line. Both of the cables 113 and 115 are endless. The cable 113extends from the bushing 111 to the right and passes over two pulleys117, 117. From the pulleys 117, 117 it extends to the left anddownwardly to two pulleys 119, 119, and from the pulleys 119, 119 itextends to the right to the guide member 110 about which it is trained.The cable 1 15 extends from the left of the bushing 111 to two pulleys121, 121 and from such pulleys passes to the right and downwardly to twopulleys 123, 123. From the latter pulleys it passes to the left and istrained about the guide member 110. From a careful consideration of FIG.11, it will therefore be obvious that as the bushing 111 is moved to theright or left, or in the illustrated Y direction, the cables 113 and 115cause the guide member 110 to also be moved in the Y direction in unisonwith the movement of the bushing. Similarly, as the bushing 111 isrotated about the illustrated vertical axis 0, by rotation of the bladeand sheath, the cables 113 and cause the guide member 110 to also berotated about the axis 0 to maintain it angularly aligned with thebushing. Of course, it should be understood that FIG. 11 is intended tobe schematic only and in an actual device additional pulleys may be usedto guide the cables in paths somewhat different from those shown.

From the foregoing consideration of the device illustrated in FIGS. 8 to11, it will be appreciated that the blade 104 and its sheath 106 may bemoved downwardly from a position above the layup 16, as illustrated inFIG. 9, while the blade is reciprocated to cause the blade to move in aplunging fashion through the layup. As the lower end of the blade andits sheath reach the guide member 110, the guide member will be properlyoriented to receive the blade and the sheath, the blade being receivedin the guide member when in the lower extent of its stroke, as shown inFIG. 8. Thereafter, as the blade is moved along a desired line of cutthe guide member 110 is moved transversely of the table in unison withthe transverse movement of the cutter head 102 to restrain the lower endof the sheath and the blade to the position of the cutter head and tothereby prevent deflection of the blade and consequent cutting errors.Also, the guide 110 includes an upwardly facing surface 130 which isflush with the top surface of the bottom member 108 and which acts tosupport the material being cut at the cutting zone to react the downwardforces imposed thereon by the blade, thereby assuring that the bottomlayer or layers of the material will be properly cut rather than beingmerely displaced into the slot 109.

In the devices described above, the free or distal end of the cuttingblade has been restrained to movement in unison with the cutter head, bya cooperating guide in the bottom member moved in unison with thetransverse movement of the cutter head, to prevent undesired deflectionof the blade. This deflection of the blade may not, however, be aproblem in some instances, and when this is the case, the guide membermay, if desired, be omitted and the bottom member used principally toaccommodate that portion of the blade which projects below or beyond thebottom surface of the layup during the cutting operation. For example,FIGS. 12 and 13 show a cutting device which is similar to the device 10of FIGS. 1 to 6, except for the construction of the various parts shownin these figures. More particularly, the cutting device illustrated bythese figures includes a bottom member 112 attached to the carriage 28for movement longitudinally of the table in unison with the longitudinalmovement of the cutter head'(not shown). The bottom member 112 includesan upwardly opening slot 114 which receives a strip of foamed plasticsuch as foamed polyethylene. The strip of plastic 116 has an uppersurface 118, generally flush with the upper surface of the remainder ofthe bottom member 112, which provides a support for the lower layers ofthe layup 16 in the vicinity of the slot 114. Additionally, the foamedstrip 116 is readily penetrable by the cutting blade, illustrated at120, the solid lines in FIG. 13 showing the blade 120 in the lowerextent of its stroke and the broken lines showing it in the upper extentof its stroke. The blade 120, as shown in FIG. 13, is used without anaccompanying sheath but if desired a sheath generally similar to thesheath 106 of FIG. 8 may be employed.

From FIGS. 12 and 13, it will be appreciated that during a cuttingoperation the blade 20 during at least a portion of its stroke extendsbeyond the lower layer of the layup and projects into the foamed strip116 which accommodates the projecting part of the blade whilenevertheless providing, by the surface 118, a support for the materialat the cutting zone so as to react the downward forces of the blade andto prevent the material from being displaced by being pushed into theslot 114 by the blade. The blade is, of course, also preferably movablevertically in addition to its reciprocating moment to enable it to bewithdrawn from and plunged into the material being cut so as to enable acut to be started from any point on the layup.

The foamed plastic strip 116 of FIGS. 12 and 13 is representative of alarge number of different penetrable materials which may be used to fillthe slot 114 of the bottom member. For example, in addition to thefoamed plastic, the slot may be filled with a self-healing material suchas that commonly referred to as Silly Putty, or a granular material suchas sawdust. FIGS. 14 and 15 show a cutting device wherein the bottommember 112 has its slot 114 filled with another preferred form offilling material constituting a plurality of bristles 122, 122. As shownin FIG. 15, the bristles 122, 122 are part of a brushlike member havinga base 124 which receives and holds the lower ends of the bristles 122,122, with the bristles 122, 122 projecting upwardly therefrom and havingtheir free ends located in a common plane substantially flush with theremainder of the surface of the bottom member 112 so that the bristlesin unison support the lower layers of the layup 16 overlying the slot114. As the blade 120 moves beyond the lower surface of the layup, itpasses into the bed of bristles 122, 122, and the bristles beingflexible tend to deflect laterally to accommodate .the blade withoutbeing cut by the latter.

In addition to the slot of the bottom member being filled with apenetrable material, it may also in some instances be left empty. Forexample, if the material being cut is relatively stiff the tendency ofthe blade to push the material into the slot of the guide member duringits downstroke may not be sufficiently great to present any problems.Also, if the material is not sufficiently stiff by itself to prevent itsbeing pushed into the slot, the layup of material on the cutting tablemay be underlaid by a layer of expendable stiff material, such as stiffpaper or cardboard, to provide a backing preventing the material frommoving into the slot and providing resistance to the downward forces ofthe blade. This construction is shown in FIGS. 16 and 17. Referring tothese figures, the bottom member 112 has its slot 114 empty and thelayup 116 is superimposed on a layer of stiff paper 126. That is, inspreading the material on the cutting table the layer 126 of paper isfirst laid down and then the various layers of material are laid up ontop of it. Both the paper 126 and layup 116 pass over the top of thebottom member 112 and as is evident from FIG. 17 the paper layer 126provides support for the bottom layers of the layup 16 to prevent themfrom being pushed into the slot 114 by the downward movement of theblade 120.

I claim:

1. A cutting device for cutting sheet material, said device comprisingmeans providing a supporting surface for supporting sheet material to becut in a spread condition, a cutter head located outwardly beyond saidsupporting surface, said cutter head having a cutting axis arrangedgenerally perpendicular to said supporting surface and having a cuttingtool which extends generally along said cutting axis toward saidsupporting surface so as to be cuttingly engageable with the sheetmaterial spread thereover, means supporting said cutter head formovement both longitudinally and transversely relative to saidsupporting surface in a plane generally parallel thereto, a bottommember extending transversely of said supporting surface and adapted toreside between said supporting surface and the sheet material spreadthereon, and means for moving said bottom member longitudinally of saidsupporting surface in unison with the movement of said cutter headlongitudinally of said supporting surface, said bottom member having aslot therein extending transversely of said supporting surface andaligned with the path of said cutting tool as said cutter head is movedtransversely of said supporting surface for receiving the distal endportion of said cutting tool.

2. A cutting device for cutting sheet material as defined in claim 1further characterized by said slot in said bottom member being filledwith a means providing a surface facing said cutter head for supportingthe material located over said slot and which surface is penetrable bysaid cutting tool.

3. A cutting device for cutting sheet material as defined in claim 2further characterized by said means filling said slot being a body offoamed plastic.

4. A cutting device for cutting sheet material as defined in claim 2further characterized by said means filling said slot being a body ofself-healing material.

5. A cutting device for cutting sheet material as defined in claim 2further characterized by said means filling said slot being a pluralityof bristles having fixed ends located at the base of said slot andhaving free ends located at the mouth of said slot.

6. A cutting device for cutting sheet material as defined in claim 1further characterized by means including an automatic controller formoving said cutter head relative to said supporting surface so as tocause said cutting tool to follow a desired line of cut relative to thesheet material spread over said supporting surface.

7. A cutting device as defined in claim 1 further char acterized by saidbottom member having a top surface engageable with said sheet material,and means for ejecting air from said top surface of said bottom memberto reduce the friction between said top surface and said material.

8. A cutting device as defuied in claim 1 further characterized by saidmeans supporting said cutter head for movement both longitudinally andtransversely relative to said supporting surface including a carriagemovable longitudinally of said supporting surface, said bottom memberbeing fixed to said carriage so as to be moved longitudinally of saidsupporting surface in unison with the longitudinal movement of saidcutter head.

9. A cutting device as defined in claim 1 further characterized by meansfor moving said cutting tool along said cutting axis toward and awayfrom said supporting surface to enable it to be withdrawn from thematerial being cut and plunged into said material at any point thereonto initiate a line of cut.

10. A cutting device for cutting sheetmaterial, said device comprisingmeans providing a supporting surface for supporting sheet material to becut in a spread condition, a cutter head located outwardly beyond saidsupporting surface, said cutter head having a cutting axis arrangedgenerally perpendicular to said supporting surface and having a cuttingtool which extends generally along said cutting axis toward saidsupporting surface so as to be cuttingly engageable with the sheetmaterial spread thereover, means supporting said cutter head formovement transversely relative to said supporting surface in a planegenerally parallel thereto, and means defining a slot located below thematerial spread on said supporting surface and extending trans verselyof said supporting surface and aligned with the path of said cuttingtool as said cutter head is moved transversely of said supportingsurface for receiving the distal end portion of said cutting tool, saidslot having a width longitudinally of said supporting surface slightlylarger than and of the same order of magnitude as the maximum dimensionof said cutting tool in the plane of said supporting surface, and saidslot being filled along substantially its entire length and width with ameans providing a surface facing said cutter head for supporting thatportion of said sheet material which is located over said slot and whichlatter surface is penetrable by said cutting tool and is stationarylongitudinally of said supporting surface relative to said cutter head.

11. A cutting device for cutting sheet material as defined in claim 10further characterized by said means filling said slot being a body offoamed plastic.

12. A cutting device for cutting sheet material as defined in claim 10further characterized by said means filling said slot being a body ofselthealing material 13. A cutting device for cutting sheet material asdefined in claim 10 further characterized by said means filling saidslot being a plurality of bristles having fixed ends located at the baseof said slot and having free ends located at the mouth of said slot.

1. A cutting device for cutting sheet material, said device comprisingmeans providing a supporting surface for supporting sheet material to becut in a spread condition, a cutter head located outwardly beyond saidsupporting surface, said cutter head having a cutting axis arrangedgenerally perpendicular to said supporting surface and having a cuttingtool which extends generally along said cutting axis toward saidsupporting surface so as to be cuttingly engageable with the sheetmaterial spread thereover, means supporting said cutter head formovement both longitudinally and transversely relative to saidsupporting surface in a plane generally parallel thereto, a bottommember extending transversely of said supporting surface and adapted toreside between said supporting surface and the sheet material spreadthereon, and means for moving said bottom member longitudinally of saidsupporting surface in unison with the movement of said cutter headlongitudinally of said supporting surface, said bottom member having aslot therein extending transversely of said supporting surface andaligned with the path of said cutting tool as said cutter head is movedtransversely of said supporting surface for receiving the distal endportion of said cutting tool.
 2. A cutting device for cutting sheetmaterial as defined in claim 1 further characterized by said slot insaid bottom member being filled with a means providing a surface facingsaid cutter head for supporting the material located over said slot andwhich surface is penetrable by said cutting tool.
 3. A cutting devicefor cutting sheet material as defined in claim 2 further characterizedby said means filling said slot being a body of foamed plastic.
 4. Acutting device for cutting sheet material as defined in claim 2 furthercharacterized by said means filling said slot being a body ofself-healing material.
 5. A cutting device for cutting sheet material asdefined in claim 2 further characterized by said means filling said slotbeing a plurality of bristles having fixed ends located at the base ofsaid slot and having free ends located at the mouth of said slot.
 6. Acutting device for cutting sheet material as defined in claim 1 furthercharacterized by means including an automatic controller for moving saidcutter head relative to said supporting surface so as to cause saidcutting tool to follow a desired line of cut relative to the sheetmaterial spread over said supporting surface.
 7. A cutting device asdefined in claim 1 further characterized by said bottom member having atop surface engageable with said sheet material, and means for ejectingair from said top surface of said bottom member to reduce the frictionbetween said top surface and said material.
 8. A cutting device asdefined in claim 1 further characterized by said means supporting saidcutter head for movement both longitudinally and transversely relativeto said supporting surface including a carriage movable longitudinallyof said supporting surface, said bottom member being fixed to saidcarriage so as to be moved longitudinally of said supporting surface inunison with the longitudinal movement of said cutter head.
 9. A cuttingdevice as defined in claim 1 further characterized by means for movingsaid cutting tool along said cutting axis toward and away from saidsupporting surface to enable it to be withdrawn from the material beingcut and plunged into said material at any point thereon to initiate aline of cut.
 10. A cutting device for cutting sheet material, saiddevice comprising means providing a supporting surface for suppOrtingsheet material to be cut in a spread condition, a cutter head locatedoutwardly beyond said supporting surface, said cutter head having acutting axis arranged generally perpendicular to said supporting surfaceand having a cutting tool which extends generally along said cuttingaxis toward said supporting surface so as to be cuttingly engageablewith the sheet material spread thereover, means supporting said cutterhead for movement transversely relative to said supporting surface in aplane generally parallel thereto, and means defining a slot locatedbelow the material spread on said supporting surface and extendingtransversely of said supporting surface and aligned with the path ofsaid cutting tool as said cutter head is moved transversely of saidsupporting surface for receiving the distal end portion of said cuttingtool, said slot having a width longitudinally of said supporting surfaceslightly larger than and of the same order of magnitude as the maximumdimension of said cutting tool in the plane of said supporting surface,and said slot being filled along substantially its entire length andwidth with a means providing a surface facing said cutter head forsupporting that portion of said sheet material which is located oversaid slot and which latter surface is penetrable by said cutting tooland is stationary longitudinally of said supporting surface relative tosaid cutter head.
 11. A cutting device for cutting sheet material asdefined in claim 10 further characterized by said means filling saidslot being a body of foamed plastic.
 12. A cutting device for cuttingsheet material as defined in claim 10 further characterized by saidmeans filling said slot being a body of selfhealing material.
 13. Acutting device for cutting sheet material as defined in claim 10 furthercharacterized by said means filling said slot being a plurality ofbristles having fixed ends located at the base of said slot and havingfree ends located at the mouth of said slot.